Multisystemic Consequences Following Oclacitinib Maleate (Apoquel®) Overdose Ingestion in Cats and Dogs.

Introduction: Pet Poison Helpline^® (PPH), a 24/7 international animal poison control center has observed a significant and rising number of exposures detailing multisystemic signs and adverse outcomes associated with oclacitinib maleate (Apoquel^®) overdoses.

Methods: Pet Poison Helpline^® utilizes a proprietary electronic database which was retrospectively reviewed for oclacitinib maleate exposure information from January 2022 to November 2024 through their toxicology consultation service.

Results: Market entry and distribution of chewable oclacitinib maleate occurred in October 2023. In the year following, there was a 299% increase in calls to PPH from inadvertent exposure. Of the 417 symptomatic cases reviewed, 63 cases were symptomatic cats, and 354 cases were symptomatic dogs. Multi-system organ involvement, including neurological, gastrointestinal, cardiovascular, renal, hepatic, and ocular signs, as well as laboratory abnormalities were observed.

Discussion: Introduction of a chewable formulation in October 2023 likely attributed to a marked increase in exposures. Accompanying this rise in overdose exposures, a notable escalation in multisystemic effects was seen, including neurological, gastrointestinal signs, cardiovascular disturbances, ocular irregularities, renal and hepatic injury, and complete blood count (CBC) hematological abnormalities. Treatment is largely symptomatic and supportive therapy.

Conclusion: The increased occurrence of exposures to oclacitinib maleate underscores necessity for additional research of JAK inhibitors in animals to better understand and address oclacitinib maleate toxicosis.